Reinsurer Gallagher Re is forecasting that insured losses from the Sept. 2 severe convective storm across the Greater Toronto Area will reach "well into the hundreds of millions" of dollars, with the full economic impact — once uninsured and underinsured damage is included — set to be substantially higher.
Storm severity and damage footprint
The event combined very large hail, damaging straight-line winds and intense rainfall over one of Canada’s most densely populated and highest-value property corridors. Golf-ball-size hail (about 4.5 centimetres) fell across large swaths of the metropolitan area, while the largest stones northwest of downtown — in and around Vaughan and North York — likely exceeded 6.3 centimetres in diameter.
Rain totals in the worst-hit zones were reported between 50 and more than 100 millimetres, producing rapid surface runoff and flash flooding that overwhelmed urban drainage systems and roadways.
- At the storm’s peak, roughly 150,000 Ontario customers lost power.
- Toronto Fire Services logged nearly 1,500 calls in the 24 hours surrounding the event — among the highest single-day volumes in the department’s records.
- Major transportation and event sites affected included Rogers Stadium in North York, the Gardiner Expressway, Bayview Avenue and the Don Valley Parkway.
How insurers view the loss and its context
Gallagher Re’s preliminary figure positions the GTA storm on a similar scale to large urban hail losses seen elsewhere in Canada, though final insured losses will depend on claim severity, policy limits and the extent of underinsurance among homeowners and businesses.
Reinsurers are particularly focused on aggregation risk in high-value corridors such as the GTA, where a single convective complex can damage thousands of properties simultaneously. The event also tracked into the northeastern United States, producing a high number of straight-line wind reports across New York, Pennsylvania and the Mid-Atlantic states — a reminder that convective systems often cross borders and widen economic exposure.
| Measured/Reported Item | Value |
|---|---|
| Hail typical size | 4.5 cm (golf-ball size) |
| Largest hail (Vaughan, North York) | > 6.3 cm |
| Rainfall | 50–100+ mm |
| Power outages | ~150,000 customers |
| Emergency calls (24 hours) | ~1,500 |
Trend: escalating hail losses in Canada
Gallagher Re places the GTA event within a worrying Canadian pattern: five of the past six years have produced annual aggregate severe convective losses that exceeded US$1 billion for insurers, with hail the principal driver. The benchmark year remains 2024, when total insured losses from convective storms reached US$2.8 billion (about C$3.8 billion), largely because of a single devastating Calgary hailstorm.
That 2024 Calgary event was initially estimated at US$2.5 billion in insurer losses. Two years after the storm, CatIQ finalised the Calgary figure at US$3.349 billion, with more than 95 per cent of claims closed — providing a rare, near-complete outcome for a major hail catastrophe and a reference point for modelling future events.
For Canadian insurers and reinsurers, the GTA storm will test underwriting parameters, catastrophe modelling and accumulation controls in a market already adapting to frequent, high-cost convective events. The size and concentration of the GTA housing stock and commercial real estate mean that even a geographically limited storm can produce a sizable concentrated loss.
As claims are lodged and adjusters work through damage assessments, the early Gallagher Re estimate is likely to be refined. Still, the preliminary number reinforces pressure on the insurance sector to reassess pricing, risk selection and mitigation incentives for homeowners and municipalities in hail-prone corridors.
For residents and business owners, the immediate priorities remain making safe repairs, documenting losses for claims, and reviewing coverage levels in the aftermath of an event that could prove costly both for policyholders and the insurance system that supports them.
